Rotary hydraulic machines

ABSTRACT

A hydraulic pump or motor of the tilting head or tilted head type including a number of separate piston and cylinder units each capable of independent pivotal movement and each including a ball and socket joint at opposite ends and a bearing slipper at one end abutting against a stationary thrust surface. The fluid is admitted and discharged from the cylinders either through the bearing slipper or through a door in the piston.

Thoma 1 ROTARY HYDRAULIC MACHINES [75]- Inventor: Jean Ulrich Thoma, Zug,

Switzerland [73] Assignee: Renzo Galdabin, Gallarate, Italy; a

part interest 22 Filed: Feb. 7, 1972 211 Appl. No.: 224,134

{30] Foreign Application Priority Data Feb. 11, 1971 Switzerland 2320/71 [52] US. Cl 91/489, 91/490, 91/507 [51] Int. Cl..... ..F01b 13/04 [58] Field of Search 91/487, 489, 490, 499, 91/507, 487 V, 489 P, 490 D, 490 A, 499 T, 507

[56] References Cited UNITED STATES PATENTS 3,240,159 3/1966 Andrews et a1 91/489 3,123,014 3/1964 Gregor 2,157,692 5/1939 Doe et a1. 91/490 2,146,133 2/1939 Tweedale 91/507 3,190,231 6/1965 Thoma 91/487 3,149,577 9/1964 Gregor 91/505 3,722,372 3/1973 Freese 91/504 FOREIGN PATENTS OR APPLICATIONS 1,161,762 1/1964 Germany 91/507 1,360,981 4/1964 France 91/499 1,453,433 6/1962 Germany 91/489 Primary Examiner-Carlton R. Croyle Assistant ExaminerGregory P. LaPointe Attorney, Agent, or FirmYoung and Thompson [57] g I ABSTRACT A hydraulic pump or motor of the tilting head or tilted head type including a number of separate piston and cylinder units each capable of independent pivotal movement and each including a ball and socket joint at opposite ends and a bearing slipper at one end abutting against a stationary thrust surface. The fluid is admitted and discharged from the cylinders either through the bearing slipper or through a door in the piston.

11 Claims, 3 Drawing Figures PATENTEB MR 1 2 I974 sum 1 or is PATENTEUHARIZ 1914 3.796137 SHEET 2 or 3 ROTARY HYDRAULIC MACHINES This invention relates to rotary hydraulic machines of the axial piston type (which term is intended to include also arrangements where the axes of the pistons are incined at less than 45 to the main rotary axis of the machine), and is particularly concerned with machines of the tilting head or tilted head type. In conventional machines of this type the cylinders are provided in a rotary cylinder block or carrier and the pistons projecting from the cylinders engage with a rotary drive member. The rotary axis of the cylinder carrier is inclined at a fixed angle or angularly adjustable in relation to the ro tary axis of the drive member so that as the two parts rotate together the individual pistons reciprocate in the cylinders, the volumetric capacity of the machine being determined by the relative angular inclination of the two main rotary axes. Various methods have been adopted hitherto for causing the roatry drive member and the rotary cylinder carrier to rotate in unison. In some machines the pistons themselves are used to transmit the driving torque between the two parts, and it has also been proposed to provide a constant velocity universal joint, or a star-shaped synchronising device, for coupling the two parts together. Such devices, however, are complicated to manufacture and assemble and suffer from a number of operating problems. On the other hand if no synchronising device is used the torque must be transmitted via the pistons and cylinders, which causes considerable geometric and kinematic problems, in addition to practical problems in making provision for the very large axial reaction forces exerted by the pistons. It is an object of the invention accordingly to provide an improved hydraulic machine of this general type which will at least partly overcome some of the existing disadvantages.

Broadly stated the invention consists in an axial piston rotary hydraulic pump or motor, of the tilted or tilting head type, comprising a rotary drive member and a rotary cylinder carrier whose rotary axes are inclined or inclinable, a plurality of separate piston and cylinder assemblies, supported individually by the cylinder carrier so as to be capable of individual pivotal movernents, and each connected to the rotary drive member, each piston and cylinder assembly including a pivotal joint at opposite ends and a bearing slipper connected to one ofthe pivotal joints and arranged to bear against a relatively stationary abutment member. Conveniently each abutment member is located at the end of the cylinder carrier remote from the rotary drive member.

In one preferred construction according to the invention the carrier has longitudinally extending guide means for each cylinder. This may be formed by a pair of spaced radial flanges on the carrier. Each flange may be formed with a bore, aligned with a corresponding bore in the other flange, and these bores may be arranged to engage the cylinder directly or indirectly. For example one of the bores at the end remote from the drive member may be arranged to locate the respective bearing slipper, which in turn locates the adjacent end of the corresponding cylinder. Alternatively one of the flanges, adjacent the drive member, may be replaced by a star-shaped member having projecting fingers designed to lie partly between the cylinders.

According to a preferred feature of the invention there is a small clearance between the guide means and the respective piston and cylinder assembly at the ends thereof adjacent to the drive member, thus permitting small tilting movements of each piston and cylinder assembly. Moreover, preferably the external surface of the cylinder, at the end thereof adjacent the drive member, is conically tapered to a smaller diameter at its end.

According to another preferred feature of the invention the drivemember has locating formations to locate the ends of the pistons, the pitch circle diameter of such formations being greater than the pitch circle diameter of the opposite ends of cylinders in the cylinder carrier.

In one construction according to the invention each bearing slipper has a flow passage communicating with the interior of the respective cylinder, and with a timing port in the cylinder carrier, the timing port communicating respectively with fluid admission and delivery ports in the abutment member as the carrier rotates. The flow ports in the abutment member will preferably be located closer to the rotary axis than the bearing slippers.

In any case each piston is preferably connected via one of the pivotal joints to an individual thrust member carried by the rotary drive member, and provided with a bearing element engaging an axial abutment surface opposing the thrust of the. pistons. Each such thrust member may be itself pivotally connected to the respective bearing element.

In an alternative construction each piston has a flow passage communicating respectively with the interior of the associated cylinder and with a timing portin the rotary drive member, the timing ports communicating successively with fluid admission and delivery ports in a non-rotary distributor member.

In any case the bearing slippers are preferably lubricated by fluid flow passages in the respective slippers, each communicating via one of the pivotal joints with the internal volumes of the respective cylinders.

The invention may be performed in various ways and two specific embodiments, with various possible modifications, will now be described by way of example with reference to the accompanying drawings, in which FIG. 1 is a somewhat diagrammatic sectional side elevation through the main operating components of an axial piston tilting head hydraulic pump or motor according to the invention,

FIG. 2 is a similar sectional side elevation through another example of the invention, and

FIG. 3 is a cross-section on a plane corresponding to the line III-III in FIG. 1, showing a modification of the first illustrated example. i

Referring first to FIG. 1, it will be assumed for convenience that the machine illustrated is a hydraulic pump, though it will be understood that the same machine can be operated as a motor. The machine includes a rotary drive shaft 10 mounted in a thurst bearing 11 from a non-rotary fixed casing member 12. The drive shaft is rigidly secured to a drive flange 13 supported by a surrounding roller bearing 14. A rotary cylinder carrier indicated generally at 15 has a stub shaft or spigot 16 fitting in a part-spherical member 17 received in a corresponding part-spherical recess at the centre of the drive flange 13. The member 17 is located by a fixing plate 18. The carrier 15 comprises a pair of radial flanges 20, 21 rigidly connected to or formed integral with a central spool 22. The flange 20 remote from the drive shaft has a series of angularly spaced cylindrical bores each receiving the cylindrical stem of a bearing slipper 26. These slippers engage the surface 27 of an abutment member 28 formed with a central bearing aperture 29 to receive and locate a projecting stub or spindle 30 on the adjacent end of the rotary carrier 15.

The abutment member 28 may be fixed with its abutment surface 27 inclined to the rotary axis 32 of the drive shaft, but in this example of an adjustable tilting head pump the abutment member 28 is rigidly connected to a pair of arms 9 mounted on trunnions indicated diagrammatically at 33, capable of rocking about a transverse tilting axis which intersects the centre 34 of the spherical joint 17. The tilting movements of the arms 9 carrying the abutment member 28 can be controlled by a conventional tilting mechanism, and cause corresponding bodily tilting movements of the whole rotary cylinder carrier 15 about the tilting axis 34, and so vary the volumetric capacity of the machine in well known manner.

Each bearing slipper 26 is formed with a partspherical socket 37 receiving a part-spherical ball head 38 at the adjacent end of the respective cylinder 40. This cylinder extends through a corresponding cylindrical aperture 41 in the other radial flange 21, the external surface of the cylinder being formed with a conical tapered surface 42, reducing in diameter towards the end of the cylinder and thus providing a small annular clearance around the cylinder where it passes through the guide aperture 41. This allows small bodily tilting movement of the cylinder about the centre of the corresponding ball and socket joint 37, 38. Within each cylinder is mounted a sliding piston 45 whose end porjects from the cylinder and is formed with a partspherical ball head 46 seating in a corresponding partspherical socket 47 formed in the rotary drive flange 13, the head being located in the socket by the fixing plate 'l8. For kinematic reasons the pitch circle diameter of the sockets 47 is slightly greater than the pitch circle diameter of the sockets 37. The piston 45 has a central flow passage 50 of substantial diameter and this communicates via the ball 46 with a flow passage 51 extending through the drive flange 13 and having a port at its opposite end which acts as a timing port to communicate successively with one of two kidneyshaped arcuate fluid delivery and admission ports in the fixed casing member 12. In FIG. 1 one of these flow ports is illustrated at 52 communicating via a passage 53 with an external hydraulic circuit.

The face of the bearing slipper 26 which engages the abutment surface 27 is lubricated by hydraulic fluid supplied from the interior volume 54 of the cylinder. For this purpose the end of the cylinder including the ball head 38 is formed with a small-bore drilling 55 which communicates with a further drilling 56 in the slipper, this in turn communicating with a shallow depression 57 formed in the end face of the slipper. The flow of hydraulic fluid to the face of the slipper for lubricating purposes can be controlled or metered by providing throttling orifices in one or more of the lubricating supply passages. For example, the throttling re striction may be provided at the co-operating spherical surfaces of the slipper 26 and the cylinder ball head 38.

In the second example of the invention illustrated in FIG. 2, parts corresponding to those of the example in FIG. 1 are indicated by the same reference numerals with an added suffix. In this example the fluid medium is admitted to and discharged from the individual cylinders from the end remote from the drive shaft 10, through passages provided in the abutment member 28. The ball head 38 at the adjacent end of each cylinder 40 has a comparatively large central flow passage 55 communicating with a similarly enlarged drilling 56' in the slipper. This drilling communicates with a transverse bore 60, and in turn with a flow passage 61 formed within the radial flange 20' of the cylinder carrier. This passage 61 opens into the axial end face of the flange, where it forms a timing port communicating with one of two kidney-shaped arcuate supply and delivery ports 62 in the non-rotary abutment member 28. Each of these ports 62 communicates with a fluid flow passage 63. In the case of a fixed capacity tilted head pump this passage 63 will communicate directly with an external hydraulic fluid circuit, but in the case of a tilting head pump as illustrated where the whole cylinder carrier 15 with the abutment member 28' can rotate about the tilting axis, the passages 63 communicate via passages within the arms 9 with flow passages in hollow trunnions 33.

In this embodiment of FIG. 2 the axial thrust of the pistons is reacted not against the rotary drive flange 13 but against the fixed casing member 12', For this purpose the drive flange is formed with a number of angularly spaced through drillings in each of which is accommodated a generally cylindrical thrust element 71 which is a sliding fit in the passage 70. This thrust element 71 has a pair of part-spherical recesses 72, 73 at opposite ends, one of which co-operates with the ball head 46' on the end of the piston 45', while the other receives a ball head 74 on a further bearing slipper 75. The bearing surface of this slipper engages against a thrust surface 76 formed on the fixed casing member 12 surrounding the drive shaft 10'. The bearing surface of each slipper is lubricated by hydraulic fluid from the internal volume 54 of the respective cylinder by small-bore passages 77, 78, 79, in the piston itself, in the thrust element 71, and in the bearing slipper 75.

The supply of oil for lubricating purposes may be throttled or metered by an appropriately shaped slot or groove 80 formed in the spherical ball head of the slipper.

In a possible modification of the embodiment illustrated in FIG. 2 the slipper 26 may be formed in two parts with an intervening ball and socket joint, one part being accurately guided as a sliding fit within the cylindrical aperture 25' of the cylinder carrier, while the actual bearing head or pad of the slipper is permitted to tilt or pivot to accommodate small angular misalignments.

Instead of an axial distributor timing valve system as illustrated in FIG. 2 a radial or pintle type timing valve and distributor may be used if preferred.

In all these examples the spherical joints between the various components, since only very small relative angular movements are involved, may be replaced by a layer of a suitable elastomeric material between the two components, having sufficient elasticity and resilience to transmit the necessary axial thrust and to permit the small angular movements due to misalignment.

In the described embodiments the ball head 38 or 38' of the cylinder 40 or 40 is located in a socket in the respective bearing slipper 26 or 26', and the slipper itself is located in the cylindrical socket in the rotary cylinder carrier. Alternatively the end of the cylinder may be directly located in the cylinder carrier, for which purpose the socket or recess in the carrier will be formed with a part-spherical surface to accommodate the small tilting movement of the cylinder.

The third example of the invention illustrated in FIG. 3 is basically similar in construction to that illustrated in FIG. 1, and only points of difference will be described, all remaining features being identical and indicated by the same reference numerals as in FIG. 1, with a double suffix. In this construction the apertures 41 in the flange 21 of the carrier (see FIG. 1) are in effect enlarged in diameter until each aperture opens into the adjacent apertures, and the surrounding hoop or ring is eliminated. The actual construction illustrated in FIG. 3 comprises a star-shaped element 80, replacing the flange 21 of FIG. 1, and formed with seven limbs or points 81 projecting outwards partly between the cylinders 40", and intervening concave arcuate surfaces 82 concentric with the individual cylinders. This construction allows somewhat greater tilting movements of the individual cylinders, The other flange of the cylinder carrier is formed with separate non-overlapping bores, similar to the bores 25 of FIG. 1.

I claim:

1. An axial piston rotary hydraulic machine of the tilted or tilting-head type, comprising a rotary drive member, a rotary cylinder carrier, means for supporting said cylinder carrier with its rotary axis inclined or inclinable relative to the axis of said drive member, a plurality of separate piston and cylinder assemblies, each assembly being supported individually by the cylinder carrier so as to be capable of individual pivotal movements relative thereto, and each connected at one end to said rotary drive member, each piston and cylinder assembly including pivotal joints at opposite ends thereof, a relatively stationary abutment member adjacent one end of said cylinder carrier; and a bearing slipper connected to one of said pivotal joints of each of said piston and cylinder assemblies and arranged to bear against said abutment member, each of said bearing slippers having a flow passage communicating with the interior of the respective cylinder, and with a timing port in the cylinder carrier, the timing port communicating respectively with fluid admission and delivery ports in said abutment member, as the carrier rotates.

2. A hydraulic machine according to claim 1, in which said abutment member is located at one end of said cylinder carrier, and said rotary drive member is located at the other end of said carrier.

3. A hydraulic machine according to claim 1, in which said cylinder carrier has longitudinally extending guide means for each cylinder.

4. A hydraulic machine according to claim 3, in which said guide means is spaced by a clearance from the respective piston and cylinder assembly, at the end thereof adjacent to said drive member, thus permitting small tilting movements of each piston and cylinder asv sembly.

5. A hydraulic machine according to claim 4, in which the external surface of each cylinder, at the end thereof adjacent the drive member, is conically tapered to a smaller diameter at its end.

6. A hydraulic machine according to claim 1, in which said drive member has locating formations to locate the ends of said pistons, the pitch circle diameter of such locating formations being greater than the pitch circle diameter of the opposite ends of the cylinders in the cylinder carrier.

7. A hydraulic machine according to claim 1, in which the radial distance of said flow ports in said abutment member from the rotary axis of said carrier is smaller than the radial distance to said bearing slippers.

8. A hydraulic machine according to claim 1, in

which each piston is pivotally connected via one of said pivotal joints to an individual thrust member carried by said rotary drive member, each thrust member being provided with a bearing element engaging an axial abutment surface opposing the thrust of the pistons.

9. A hydraulic machine according to claim 8, in which. each of said thrust members is pivotally connected to the respective bearing element.

10. A hydraulic machine according to claim 1, in which said bearing slippers are lubricated by fluid flow passages in the respective slippers, each communicating via one of said pivotal joints with th internal volumes of the respective cylinders.

11. An axial piston rotary hydraulic machine of the tilted or tilting head type, comprising a rotary drive member, a rotary cylinder carrier, means for supporting said cylinder carrier with its rotary axis inclined or inclinable relative to the 'axis of said drive member, a plurality of separate piston and cylinder assemblies, each assembly being supported individually by the cylinder carrier so as to be capable of individual pivotal movements relative thereto, and each connected at one end to said rotary drive member, each piston and cylinder assembly including pivotal joints at opposite ends thereof, a relatively stationary abutment member adjacent one end of said cylinder carrier, and a bearing slipper connected to one of said pivotal joints of each of said piston and cylinder assemblies and arranged to bear against said abutment member, each piston having a flow passage communicating respectively with the interior of the associated cylinder and with a timing port in the rotary drive member, the timing ports communicating successively with fluid admission and delivery ports in a non-rotary distributor member. 

1. An axial piston rotary hydraulic machine of the tilted or tilting head type, comprising a rotary drive member, a rotary cylinder carrier, means for supporting said cylinder carrier with its rotary axis inclined or inclinable relative to the axis of said drive member, a plurality of separate piston and cylinder assemblies, each assembly being supported individually by the cylinder carrier so as to be capable of individual pivotal movements relative thereto, and each connected at one end to said rotary drive member, each piston and cylinder assembly including pivotal joints at opposite ends thereof, a relatively stationary abutment member adjacent one end of said cylinder carrier, and a bearing slipper connected to one of said pivotal joints of each of said piston and cylinder assemblies and arranged to bear against said abutment member, each of said bearing slippers having a flow passage communicating with the interior of the respective cylinder, and with a timing port in the cylinder carrier, the timing port communicating respectively with fluid admission and delivery ports in said abutment member, as the carrier rotates.
 2. A hydraulic machine according to claim 1, in which said abutment member is located at one end of said cylinder carrier, and said rotary drive member is located at the other end of said carrier.
 3. A hydraulic machine according to claim 1, in which said cylinder carrier has longitudinally extending guide means for each cylinder.
 4. A hydraulic machine according to claim 3, in which said guide means is spaced by a clearance from the respective piston and cylinder assembly, at the end thereof adjacent to said drive member, thus permitting small tilting movements of each piston and cylinder assembly.
 5. A hydraulic machine according to claim 4, in which the external surface of each cylinder, at the end thereof adjacent the drive member, is conically tapered to a smaller diameter at its end.
 6. A hydraulic machine according to claim 1, in which said drive member has locating formations to locate the ends of said pistons, the pitch circle diameter of such locating formations being greater than the pitch circle diameter of the opposite ends of the cylinders in the cylinder carrier.
 7. A hydraulic machine according to claim 1, in which the radial distance of said flow ports in said abutment member from the rotary axis of said carrier is smaller than the radial distance to said bearing slippers.
 8. A hydraulic machine according to claim 1, in which each piston is pivotally connected via one of said pivotal joints to an individual thrust member carried by said rotary drive member, each thrust member being provided with a bearing element engaging an axial abutment surface opposing the thrust of the pistons.
 9. A hydraulic machine according to claim 8, in which each of said thrust members is pivotally connected to the respective bearing element.
 10. A hydraulic machine according to claim 1, in which said bearing slippers are lubricated by fluid flow passages in the respective slippers, each communicating via one of said pivotal joints with th internal volumes of the respective cylinders.
 11. An axial piston rotary hydraulic machine of the tilted or tilting head type, comprising a rotary drive member, a rotary cylinder carrier, means for supporting said cylinder carrier with its rotary axis inclined or inclinable relative to the axis of said drive member, a plurality of separate piston and cylindeR assemblies, each assembly being supported individually by the cylinder carrier so as to be capable of individual pivotal movements relative thereto, and each connected at one end to said rotary drive member, each piston and cylinder assembly including pivotal joints at opposite ends thereof, a relatively stationary abutment member adjacent one end of said cylinder carrier, and a bearing slipper connected to one of said pivotal joints of each of said piston and cylinder assemblies and arranged to bear against said abutment member, each piston having a flow passage communicating respectively with the interior of the associated cylinder and with a timing port in the rotary drive member, the timing ports communicating successively with fluid admission and delivery ports in a non-rotary distributor member. 